MCM-41 supported S-alkyl/aryl-substituted 2-mercaptobenzothiazolium-based ionic liquids: synthesis, characterization, and application in the fuel desulfurization

Abstract

Supported ionic liquids (SILs), synthesized by immobilization of ionic liquids (ILs) onto solid support materials, have played an effective role in several applications like fuel desulfurization, organic catalysis, gas separations, biofuel synthesis, etc., in comparison to pure ILs which suffer from many drawbacks like difficult recovery, high cost, mass transfer issue owing to large viscosity, toxic nature, complications in product purifications and fixed bed reactor technology. In this study, a series of new SILs (MCM-41@[S-RBTh][Cl]; R = aryl/alkyl groups) were synthesized via immobilization of different S-alkyl/aryl-substituted 2-mercaptobenzothiazolium-based ILs onto MCM-41 silica support. Structure elucidation of SILs was achieved through SEM, EDS, SAXS, NMR, BET, and FT-IR spectroscopy. Further, the synthesized SILs and MCM-41 were investigated for the removal of sulfur-containing aromatic species from model gasoline and real gasoline. MCM-41@[S-BzBTh][Cl] (0.5 g) removed maximum sulfur content with the percentage of 57.5 % (at 35 °C), 58.7 % (at 40 °C), and 63.4 % (at 45 °C) of TS, TN, and DBT respectively, from model gasoline (5 g) of sulfur concentration of 200 ppm under shaking conditions for 140 min. The impact of the aryl group and different lengths of alkyl groups of supported benzothiazolium-based ILs on their adsorption performance was also studied.